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marcus.erl |
/*
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* include/linux/hrtimer.h
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*
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* hrtimers - High-resolution kernel timers
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*
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* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
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*
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* data type definitions, declarations, prototypes
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*
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* Started by: Thomas Gleixner and Ingo Molnar
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*
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* For licencing details see kernel-base/COPYING
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*/
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#ifndef _LINUX_HRTIMER_H
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#define _LINUX_HRTIMER_H
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#include <linux/rbtree.h>
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#include <linux/ktime.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/wait.h>
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struct hrtimer_clock_base;
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struct hrtimer_cpu_base;
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/*
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* Mode arguments of xxx_hrtimer functions:
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*/
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enum hrtimer_mode {
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HRTIMER_MODE_ABS, /* Time value is absolute */
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HRTIMER_MODE_REL, /* Time value is relative to now */
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};
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/*
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* Return values for the callback function
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*/
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enum hrtimer_restart {
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HRTIMER_NORESTART, /* Timer is not restarted */
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HRTIMER_RESTART, /* Timer must be restarted */
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};
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/*
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* hrtimer callback modes:
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*
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* HRTIMER_CB_SOFTIRQ: Callback must run in softirq context
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* HRTIMER_CB_IRQSAFE: Callback may run in hardirq context
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* HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and
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* does not restart the timer
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* HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in hardirq context
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* Special mode for tick emultation
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*/
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enum hrtimer_cb_mode {
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HRTIMER_CB_SOFTIRQ,
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HRTIMER_CB_IRQSAFE,
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HRTIMER_CB_IRQSAFE_NO_RESTART,
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HRTIMER_CB_IRQSAFE_NO_SOFTIRQ,
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};
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/*
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* Values to track state of the timer
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*
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* Possible states:
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*
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* 0x00 inactive
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* 0x01 enqueued into rbtree
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* 0x02 callback function running
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* 0x04 callback pending (high resolution mode)
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*
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* Special case:
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* 0x03 callback function running and enqueued
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* (was requeued on another CPU)
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* The "callback function running and enqueued" status is only possible on
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* SMP. It happens for example when a posix timer expired and the callback
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* queued a signal. Between dropping the lock which protects the posix timer
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* and reacquiring the base lock of the hrtimer, another CPU can deliver the
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* signal and rearm the timer. We have to preserve the callback running state,
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* as otherwise the timer could be removed before the softirq code finishes the
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* the handling of the timer.
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*
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* The HRTIMER_STATE_ENQUEUE bit is always or'ed to the current state to
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* preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
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*
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* All state transitions are protected by cpu_base->lock.
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*/
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#define HRTIMER_STATE_INACTIVE 0x00
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#define HRTIMER_STATE_ENQUEUED 0x01
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#define HRTIMER_STATE_CALLBACK 0x02
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#define HRTIMER_STATE_PENDING 0x04
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/**
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* struct hrtimer - the basic hrtimer structure
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* @node: red black tree node for time ordered insertion
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* @expires: the absolute expiry time in the hrtimers internal
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* representation. The time is related to the clock on
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* which the timer is based.
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* @function: timer expiry callback function
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* @base: pointer to the timer base (per cpu and per clock)
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* @state: state information (See bit values above)
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* @cb_mode: high resolution timer feature to select the callback execution
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* mode
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* @cb_entry: list head to enqueue an expired timer into the callback list
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* @start_site: timer statistics field to store the site where the timer
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* was started
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* @start_comm: timer statistics field to store the name of the process which
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* started the timer
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* @start_pid: timer statistics field to store the pid of the task which
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* started the timer
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*
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* The hrtimer structure must be initialized by hrtimer_init()
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*/
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struct hrtimer {
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struct rb_node node;
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ktime_t expires;
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enum hrtimer_restart (*function)(struct hrtimer *);
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struct hrtimer_clock_base *base;
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unsigned long state;
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#ifdef CONFIG_HIGH_RES_TIMERS
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enum hrtimer_cb_mode cb_mode;
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struct list_head cb_entry;
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#endif
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#ifdef CONFIG_TIMER_STATS
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void *start_site;
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char start_comm[16];
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int start_pid;
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#endif
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};
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/**
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* struct hrtimer_sleeper - simple sleeper structure
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* @timer: embedded timer structure
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* @task: task to wake up
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*
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* task is set to NULL, when the timer expires.
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*/
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struct hrtimer_sleeper {
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struct hrtimer timer;
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struct task_struct *task;
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};
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/**
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* struct hrtimer_clock_base - the timer base for a specific clock
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* @cpu_base: per cpu clock base
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* @index: clock type index for per_cpu support when moving a
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* timer to a base on another cpu.
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* @active: red black tree root node for the active timers
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* @first: pointer to the timer node which expires first
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* @resolution: the resolution of the clock, in nanoseconds
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* @get_time: function to retrieve the current time of the clock
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* @get_softirq_time: function to retrieve the current time from the softirq
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* @softirq_time: the time when running the hrtimer queue in the softirq
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* @cb_pending: list of timers where the callback is pending
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* @offset: offset of this clock to the monotonic base
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* @reprogram: function to reprogram the timer event
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*/
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struct hrtimer_clock_base {
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struct hrtimer_cpu_base *cpu_base;
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clockid_t index;
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struct rb_root active;
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struct rb_node *first;
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ktime_t resolution;
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ktime_t (*get_time)(void);
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ktime_t (*get_softirq_time)(void);
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ktime_t softirq_time;
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#ifdef CONFIG_HIGH_RES_TIMERS
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ktime_t offset;
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int (*reprogram)(struct hrtimer *t,
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struct hrtimer_clock_base *b,
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ktime_t n);
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#endif
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};
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#define HRTIMER_MAX_CLOCK_BASES 2
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/*
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* struct hrtimer_cpu_base - the per cpu clock bases
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* @lock: lock protecting the base and associated clock bases
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* and timers
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* @lock_key: the lock_class_key for use with lockdep
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* @clock_base: array of clock bases for this cpu
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* @curr_timer: the timer which is executing a callback right now
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* @expires_next: absolute time of the next event which was scheduled
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* via clock_set_next_event()
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* @hres_active: State of high resolution mode
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* @check_clocks: Indictator, when set evaluate time source and clock
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* event devices whether high resolution mode can be
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* activated.
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* @cb_pending: Expired timers are moved from the rbtree to this
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* list in the timer interrupt. The list is processed
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* in the softirq.
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* @nr_events: Total number of timer interrupt events
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*/
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struct hrtimer_cpu_base {
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spinlock_t lock;
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struct lock_class_key lock_key;
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struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
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#ifdef CONFIG_HIGH_RES_TIMERS
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ktime_t expires_next;
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int hres_active;
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struct list_head cb_pending;
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unsigned long nr_events;
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#endif
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};
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#ifdef CONFIG_HIGH_RES_TIMERS
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struct clock_event_device;
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extern void clock_was_set(void);
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extern void hres_timers_resume(void);
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extern void hrtimer_interrupt(struct clock_event_device *dev);
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/*
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* In high resolution mode the time reference must be read accurate
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*/
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static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
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{
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return timer->base->get_time();
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}
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/*
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* The resolution of the clocks. The resolution value is returned in
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* the clock_getres() system call to give application programmers an
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* idea of the (in)accuracy of timers. Timer values are rounded up to
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* this resolution values.
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*/
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# define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 }
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# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
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#else
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# define KTIME_MONOTONIC_RES KTIME_LOW_RES
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/*
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* clock_was_set() is a NOP for non- high-resolution systems. The
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* time-sorted order guarantees that a timer does not expire early and
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* is expired in the next softirq when the clock was advanced.
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*/
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static inline void clock_was_set(void) { }
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static inline void hres_timers_resume(void) { }
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/*
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* In non high resolution mode the time reference is taken from
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* the base softirq time variable.
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*/
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static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
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{
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return timer->base->softirq_time;
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}
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#endif
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extern ktime_t ktime_get(void);
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extern ktime_t ktime_get_real(void);
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/* Exported timer functions: */
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/* Initialize timers: */
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extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
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enum hrtimer_mode mode);
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/* Basic timer operations: */
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extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
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const enum hrtimer_mode mode);
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extern int hrtimer_cancel(struct hrtimer *timer);
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extern int hrtimer_try_to_cancel(struct hrtimer *timer);
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static inline int hrtimer_restart(struct hrtimer *timer)
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{
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return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
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}
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| 273 |
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/* Query timers: */
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extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
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extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
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extern ktime_t hrtimer_get_next_event(void);
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| 278 |
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/*
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* A timer is active, when it is enqueued into the rbtree or the callback
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* function is running.
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*/
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static inline int hrtimer_active(const struct hrtimer *timer)
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{
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return timer->state != HRTIMER_STATE_INACTIVE;
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}
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/*
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| 289 |
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* Helper function to check, whether the timer is on one of the queues
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*/
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static inline int hrtimer_is_queued(struct hrtimer *timer)
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{
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return timer->state &
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(HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
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}
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| 296 |
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| 297 |
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/* Forward a hrtimer so it expires after now: */
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extern unsigned long
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hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
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| 300 |
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| 301 |
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/* Precise sleep: */
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| 302 |
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extern long hrtimer_nanosleep(struct timespec *rqtp,
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struct timespec *rmtp,
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| 304 |
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const enum hrtimer_mode mode,
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const clockid_t clockid);
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extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
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extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
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struct task_struct *tsk);
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/* Soft interrupt function to run the hrtimer queues: */
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extern void hrtimer_run_queues(void);
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| 314 |
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/* Bootup initialization: */
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extern void __init hrtimers_init(void);
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| 317 |
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#if BITS_PER_LONG < 64
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extern unsigned long ktime_divns(const ktime_t kt, s64 div);
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#else /* BITS_PER_LONG < 64 */
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# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
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#endif
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| 322 |
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| 323 |
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/* Show pending timers: */
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| 324 |
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extern void sysrq_timer_list_show(void);
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| 325 |
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| 326 |
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/*
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| 327 |
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* Timer-statistics info:
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*/
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| 329 |
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#ifdef CONFIG_TIMER_STATS
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| 331 |
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extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
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| 332 |
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void *timerf, char *comm,
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| 333 |
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unsigned int timer_flag);
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| 334 |
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| 335 |
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static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
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| 336 |
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{
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| 337 |
|
|
timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
|
| 338 |
|
|
timer->function, timer->start_comm, 0);
|
| 339 |
|
|
}
|
| 340 |
|
|
|
| 341 |
|
|
extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
|
| 342 |
|
|
void *addr);
|
| 343 |
|
|
|
| 344 |
|
|
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
|
| 345 |
|
|
{
|
| 346 |
|
|
__timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
|
| 347 |
|
|
}
|
| 348 |
|
|
|
| 349 |
|
|
static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
|
| 350 |
|
|
{
|
| 351 |
|
|
timer->start_site = NULL;
|
| 352 |
|
|
}
|
| 353 |
|
|
#else
|
| 354 |
|
|
static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
|
| 355 |
|
|
{
|
| 356 |
|
|
}
|
| 357 |
|
|
|
| 358 |
|
|
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
|
| 359 |
|
|
{
|
| 360 |
|
|
}
|
| 361 |
|
|
|
| 362 |
|
|
static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
|
| 363 |
|
|
{
|
| 364 |
|
|
}
|
| 365 |
|
|
#endif
|
| 366 |
|
|
|
| 367 |
|
|
#endif
|
